THE ESTABLISHMENT OF THE PATTERNS OF FORCE LOADS ON AN UNMANNED AERIAL VEHICLE BASED ON THE PARAMETERS OF FIRE-EXTINGUISHING AGENT SUPPLY THROUGH A FIRE NOZZLE

Abstract

The object of the study is the process of forming force loads during the supply of fire extinguishing agents through a fire hose held by an unmanned aerial vehicle. The problem that was solved in the study is the lack of cal­culation models of the joint action of the jet stream and the tension of the vertical hose line on a multirotor unmanned aerial vehi­cle during high­altitude fire extinguishing, which complicates the selection of the hose mounting parameters and compensation for destabilizing moments. Empirical data were obtained on the distribution of reactive and static forces during the supply of fire extin­guishing agents in the fastening nodes of the hose line suspension system and the fire hose using the developed installation at alti­tudes of 30­50 m. It was established that with increasing altitude, primarily the static load on the suspension system increases. After sta­bilization of the supply mode, the value of the force F6 is 340–350 N at an altitude of 30 m, 366–390 N at an altitude of 40 m, and 396–428 N at an altitude of 50 m. The reactive force F5had lower values, but increased with increas­ing pressure and nozzle diameter. At an alti­tude of 40 m, the force F5 was 33–45 N. At 50 m, for a nozzle with a diameter of 5 mm, it was 34–49 N, for a nozzle with a diameter of 6 mm, it was 54 N, and for a nozzle with a diame­ter of 7 mm, it was 57 N. The highest loads were recorded at a pressure of 8 bar and noz­zle diameters of 6–7 mm. The results show that the altitude determines mainly the stat­ic load, and the reactive force depends on the pressure and nozzle diameter. For the math­ematical description, a full factorial experi­ment was used with the factors of the time of supply of fire extinguishing agents, pressure, and nozzle diameter. Interpolation regression relationships for reactive forces F1–F5 were obtained. The tension force F6 is described by a quadratic model taking into account time and altitude. A feature of the study is a comprehensive assessment of the jet reac­tive force, tension force and loads at the bar­rel fixation points. The obtained patterns are significant in view of the increasingly wide­spread integration of unmanned aerial vehi­cles into the firefighting industry. The results can be used to substantiate the design para­meters of unmanned aerial vehicles during their design